JP2008064252A - Tripod type constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the number of components of a tripod type constant velocity universal joint allowing oscillation of a roller with respect to tripod leg shafts and achieve unitization of the roller and rolling elements (rollers) to improve efficiency of assembling work. <P>SOLUTION: The tripod type constant velocity universal joint is provided with spherical parts 55a formed on the outer peripheral faces of the tripod leg shafts 55 of the tripod type constant velocity universal joint; the plurality of rollers 56 arranged in annular spaces between the spherical face parts 55a of the leg shafts 55 and the inner diameter face of the roller 57; shaft parts 56a, 56b protruded from centers of both ends of the rollers 56 to the axial directions of the rollers 56; and guide parts (annular groove parts 57b of flange parts 57a, annular groove parts 58a of snap rings 58) for guiding the shaft parts 56a, 56b to move them in the circumferential direction of the roller 57. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sliding tripod type constant velocity universal joint used in power transmission devices such as automobiles and various industrial machines, and in particular, a plurality of spherical portions formed on the outer peripheral surface of a leg shaft of a tripod and a plurality of rollers. The present invention relates to a tripod type constant velocity universal joint provided with rollers.

  The tripod type constant velocity universal joint includes a hollow cylindrical housing as an outer joint member, a tripod as an inner joint member, and a roller as a torque transmission member as main components.

  The housing is composed of an integrally formed mouse portion and stem portion. The mouse portion has a cup shape opened at one end, and a track groove extending in the axial direction is formed at a position of the inner circumference in the circumferential direction. The mouse part has a non-cylindrical shape in which a large-diameter part and a small-diameter part appear alternately when viewed in cross section. That is, the mouth portion is formed with a large diameter portion and a small diameter portion, so that the three track grooves extending in the axial direction are formed on the inner peripheral surface thereof. Roller guide surfaces are formed on the side walls facing each other in the circumferential direction of each track groove. The stem portion is coupled to the first rotating shaft.

  The tripod includes a boss and a leg shaft. The boss is formed with a spline or serration hole that is coupled to the second rotating shaft so as to transmit torque. The leg shaft protrudes in the radial direction from the circumferentially divided position of the boss. Each leg shaft of the tripod supports the roller rotatably. The roller includes a double roller type having an inner roller and an outer roller and only a single roller type.

  As single roller type sliding type constant velocity universal joints, there are those described in Patent Document 1 (Japanese Patent Laid-Open No. Sho 62-233522) and those described in Patent Document 2 (Japanese Patent Laid-Open No. 2004-2575769). Are known.

  This single roller type sliding constant velocity universal joint includes a housing 1, a tripod 4 and a roller 7 as shown in FIGS. 6 (A) and 6 (B), for example. Three cylindrical concave grooves or track grooves 2 are formed in the axial direction of the inner peripheral surface of the housing 1. A tripod 4 is inserted into the housing 1. An annular roller 7 is rotatably fitted on the cylindrical outer peripheral surface of the three leg shafts 5 protruding in the radial direction of the tripod 4 via a plurality of needle rollers 6. It is inserted into the track groove 2. The pair of roller guide surfaces 3 facing each other in the circumferential direction of each track groove 2 is a concave curved surface parallel to the axial direction, and the outer peripheral surface of each roller 7 is a convex curved surface adapted to the roller guide surface 3. Each roller 7 is movable along the track groove 2 while engaging with the roller guide surface 3 of the corresponding track groove 2 and rotating around the leg shaft 5. In this tripod type constant velocity universal joint, the drive shaft (first rotation shaft) is connected to the housing 1, and the driven shaft (second rotation shaft) is connected to the tripod 4.

  When the leg shaft 5 of the tripod 4 and the roller guide surface 3 of the housing 1 are engaged in the biaxial rotation direction via the roller 7, the rotational torque is transmitted from the drive side to the driven side at a constant speed. Further, as each roller 7 rolls on the roller guide surface 3 while rotating with respect to the leg shaft 5, relative axial displacement and angular displacement between the housing 1 and the tripod 4 are absorbed.

  In the single roller type sliding type constant velocity universal joint shown in FIGS. 6 (A) and 6 (B), vehicle shudder due to the third-order induced thrust is likely to occur. As means for solving this shudder, a double roller type sliding type constant velocity universal joint has been proposed in Patent Document 3 (JP 2000-320563 A), Patent Document 4 (JP 2001-132766 A), and the like. .

  In this double roller type sliding type constant velocity universal joint, for example, as shown in FIGS. 7A and 7B, a roller cassette C is fitted to a leg shaft 22 of a tripod 20 so as to swing freely. . The roller cassette C is constituted by an assembly body including an inner roller 32, an outer roller 34, and needle rollers 36 interposed between the two rollers.

  The housing 10 has three track grooves 12 extending in the axial direction on the inner peripheral surface. Roller guide surfaces 14 are formed on the side walls of each track groove 12 facing each other in the circumferential direction. The tripod 20 has three leg shafts 22 protruding in the radial direction, and a roller cassette C is attached to each leg shaft 22. The outer roller 34 of the roller cassette C is accommodated in the track groove 12 of the housing 10. The outer peripheral surface of the outer roller 34 is a convex curved surface that matches the roller guide surface 14.

  An inner roller 32 is fitted on the outer peripheral surface of the leg shaft 22. The inner roller 32 and the outer roller 34 are unitized via a plurality of needle rollers 36 to constitute a roller cassette C that can rotate relative to each other. That is, the cylindrical outer peripheral surface of the inner roller 32 is used as an inner raceway surface, and the cylindrical inner peripheral surface of the outer roller 34 is used as an outer raceway surface.

  As shown in FIG. 7B, the needle roller 36 is incorporated in a so-called full roller state in which as many rollers as possible are inserted and there is no cage. Reference numerals 33 and 35 indicate a pair of washers attached to an annular groove formed on the inner peripheral surface of the outer roller 34 to prevent the needle rollers 36 from falling off. These washers 33 and 35 have a cut at one place in the circumferential direction, and are mounted in an annular groove on the inner peripheral surface of the outer roller 34 in a state of being elastically reduced in diameter.

  The outer circumferential surface of the leg shaft 22 has a straight shape parallel to the axis of the leg shaft 22 as shown in FIG. 7A when viewed in a vertical section, and the long axis as shown in FIG. 7B when viewed in a cross section. It has an elliptical shape orthogonal to the joint axis. The cross-sectional shape of the leg shaft 22 is substantially elliptical by reducing the thickness seen in the axial direction of the tripod 20. In other words, the cross-sectional shape of the leg shaft 22 is such that the surfaces facing each other in the axial direction of the tripod 20 are retracted in the mutual direction, that is, on the smaller diameter side than the virtual cylindrical surface.

  The inner peripheral surface of the inner roller 32 has an arcuate convex cross section as shown in FIG. That is, the generatrix of the inner peripheral surface is a convex arc with a radius r. Since the cross-sectional shape of the leg shaft 22 is substantially elliptical as described above and a predetermined clearance is provided between the leg shaft 22 and the inner roller 32, the inner roller 32 has a leg shaft. In addition to being able to move 22 in the axial direction, it is also swingable with respect to the leg shaft 22.

  Further, as described above, the inner roller 32 and the outer roller 34 are unitized so as to be rotatable relative to each other via the needle rollers 36. Therefore, the inner roller 32 and the outer roller 34 swing as a unit with respect to the leg shaft 22. It is in a swingable relationship. Here, swinging means that the axes of the inner roller 32 and the outer roller 34 are inclined with respect to the axis of the leg shaft 22 in a plane including the axis of the leg shaft 22.

In this double roller type tripod type constant velocity universal joint, the roller cassette C is swingable and swingable (the roller cassette C is tiltable and axially displaceable with respect to the leg shaft 22). When the rotational force is transmitted with the operating angle 20 at an angle, the outer roller 34 and the roller guide surface 14 can be prevented from being obliquely crossed, and the outer roller 34 is parallel to the axis of the housing 10. It is guided by the roller guide surface 14 of the housing 10 so as to maintain the posture, and rolls on the roller guide surface 14 in the same posture. Therefore, the slip resistance during the operating angle operation is reduced, and the generation of the slide resistance and the third-order induced thrust is suppressed.
JP-A-62-233522 JP 2004-25769 A JP 2000-320563 A JP 2001-132766 A Japanese Patent Laid-Open No. 10-184715 Japanese Patent No. 3385343

  However, if the roller is a double roller, the number of parts increases and the cost increases. In order to solve this problem, a tripod type constant velocity universal joint in which the inner roller is omitted was proposed in Patent Document 5 (Japanese Patent Laid-Open No. 10-184715). However, the proposed one has a problem in assembling workability of the constant velocity universal joint because the roller and the rolling element (roller) are not unitized.

  As a method for unitizing the roller and the rolling element (roller), there is a so-called keystone method as proposed in Patent Document 6 (Japanese Patent No. 3385343). There is a limit to the number relationship.

  An object of the present invention is to solve the above-described problems.

  In order to solve the above-mentioned problem, the invention of claim 1 is directed to a first rotary shaft that is formed at one end side in the axial direction and has a groove extending in the axial direction at a circumferentially equally divided position on the inner peripheral surface. A tripod having a hollow cylindrical housing fixed to the end, a boss fixed to the end of the second rotating shaft, and a leg shaft protruding in a radial direction from a circumferentially divided position of the boss; In a tripod type constant velocity universal joint that is fitted in the outer peripheral surface of the leg shaft and is accommodated in a groove in the housing and is rollable in the housing axial direction, a spherical surface formed on the outer peripheral surface of the leg shaft of the tripod A plurality of rollers disposed in an annular space between the spherical surface portion of the leg shaft and the inner diameter surface of the roller, a shaft portion projecting in the axial direction of the roller from the center of both ends of the roller, and the shaft And a guide part that guides the part so as to be movable in the circumferential direction of the roller. And wherein the door.

  In the conventional single roller type tripod type constant velocity universal joint, when the constant velocity universal joint rotates at an angle, the roller operates while being inclined with respect to the housing track groove together with the inclination of the tripod leg shaft. Since the inclination of the journal can be absorbed between the roller and the leg shaft, the roller can be rolled parallel to the housing track groove. Therefore, it is possible to reduce the rotational thrust induced thrust and reduce the vehicle shudder phenomenon.

  The invention of claim 2 is characterized in that a belt-like intermediate curved surface portion having a radius of curvature larger than the radius of curvature of the spherical surface portion is formed at a predetermined width at the central equator portion of the spherical surface portion.

  Thereby, the surface pressure between the leg shafts can be reduced and the joint life can be increased.

  The invention of claim 3 is characterized in that the guide portion is constituted by a pair of annular groove portions for receiving shaft portions at both ends of the roller.

  By guiding the shaft portions at both ends of the roller with the annular groove portion, the roller can stably circulate along the inner diameter surface of the roller.

  The invention of claim 4 is characterized in that at least one of the pair of annular grooves is formed on an inner surface of a retaining ring fixed to an inner diameter surface of the roller.

  By using a retaining ring with an annular groove, the roller can be easily assembled to the roller. Further, the roller can be unitized, and joint assembly and parts management are simplified.

  The invention according to claim 5 is characterized in that one of the pair of annular groove portions is formed on an inner surface of a flange portion integrally formed on an inner diameter surface of the roller.

  By forming one of the annular grooves on the inner surface of the flange portion of the roller, only one retaining ring is required, and the assembly workability is improved.

  The invention of claim 6 is characterized in that the snap ring can be elastically expanded and contracted by forming a slit at one place in the circumferential direction.

  Assembling workability is improved by making the snap ring elastically expandable and contractible.

According to the tripod type constant velocity universal joint of the present invention, since there is a single roller, the number of parts is less than that of the double roller type tripod type constant velocity universal joint, and the cost and size of the joint can be reduced. In addition, since the inclination of the tripod leg shaft is allowed by the slip between the roller contacting the spherical surface of the leg shaft, it is possible to roll the inner ring groove in parallel without tilting the roller. Rotational tertiary induced thrust can be reduced and vehicle shudder phenomenon can be reduced.
In addition, it is possible to unitize the rollers by projecting shafts at both ends of a plurality of rollers and fixing a retaining ring having an annular groove that guides one of the shafts to the inner diameter surface of the roller. Thus, the assembly workability of the joint can be improved.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 3 show the first embodiment, FIG. 4 shows the second embodiment, and FIG. 5 shows the third embodiment.

  As shown in FIG. 1, the tripod constant velocity universal joint includes a housing 51, a tripod 54, and a roller 57. The housing 51 is fixed to the end of the first rotating shaft, and three cylindrical concave grooves or track grooves 52 are formed in the axial direction of the inner peripheral surface thereof. A tripod 54 is inserted into the housing 51. The tripod 54 includes a boss 62 and three leg shafts 55 protruding in the radial direction. The boss 62 is formed with a spline or serration hole that is coupled to the second rotating shaft so as to be able to transmit torque. The outer peripheral surface of the three leg shafts 55 is a spherical surface portion 55a (curvature radius R), and a plurality of cylindrical rollers 56 are interposed in the spherical surface portion 55a in a full roller state without any gaps, and the inner diameter surface of the roller 57. Are fitted. The roller 57 is inserted along the track groove 52 so as to roll freely. The cylindrical roller 56 is unitized with a roller 57 by a retaining ring 58 described later.

  A pair of roller guide surfaces 53 facing each other in the circumferential direction of each track groove 52 is a concave curved surface parallel to the axial direction, and an outer peripheral surface of each roller 57 is a convex curved surface adapted to the roller guide surface 53. Each roller 57 is movable along the track groove 52 while engaging with the roller guide surface 53 of the corresponding track groove 52 and rotating around the leg shaft 55. In this tripod type constant velocity universal joint, the drive shaft (first rotation shaft) is connected to the housing 51, and the driven shaft (second rotation shaft) is connected to the tripod 54.

  When the leg shaft 55 of the tripod 54 and the roller guide surface 53 of the housing 51 are engaged with each other in the biaxial rotation direction via the roller 57, the rotational torque is transmitted from the drive side to the driven side at a constant speed. Further, as each roller 57 rolls on the roller guide surface 53 while rotating with respect to the leg shaft 55, relative axial displacement and angular displacement between the housing 51 and the tripod 54 are absorbed.

  As shown in FIG. 2, shaft portions 56 a and 56 b having a predetermined length are integrally projected at the center of both ends of the cylindrical roller 56 along the axial direction of the cylindrical roller 56. It is sufficient that the length of the shaft portions 56a and 56b is actually several millimeters. The shaft portions 56a and 56b at both ends of the roller need not have the same length, but desirably the shaft portions 56a and 56b at both ends have the same length so as not to have directionality. The tips of the shaft portions 56a and 56b are preferably finished as appropriate R surfaces.

  A flange portion 57a is integrally formed on the inner diameter surface of the roller 57 from the side close to the joint center inward in the radial direction, that is, toward the leg shaft 55. The length of the flange portion 57a is a length that does not interfere with the tripod 54 or the leg shaft 55 even when the joint rotates at a required maximum operating angle. An annular groove 57b is formed concentrically with the inner diameter surface of the roller 57 on the inner surface of the flange portion 57a, that is, the surface opposite to the joint center. The annular groove portion 57b has a substantially rectangular cross section so that the shaft portion 56a of the cylindrical roller 56 can be loosely fitted, and the two corner portions have appropriate R surfaces 57c. Further, an R groove 57d for avoiding interference with an end surface corner portion of the cylindrical roller 56 is formed at a corner portion between the flange portion 57a and the inner diameter surface.

  On the inner diameter surface of the roller 57, an annular groove 57e is formed at a predetermined depth on the side far from the joint center. The outer peripheral edge of the retaining ring 58 is fitted into the groove portion 57e. The retaining ring 58 is formed by punching a steel plate in an annular shape and press-molding an annular groove 58a having a U-shaped cross section near the center in the radial width direction. The sectional shape of the annular groove portion 58a may be the same as the sectional shape of the annular groove portion 57b of the flange portion 57a of the roller 57 so that the shaft portion 56b of the cylindrical roller 56 can be loosely fitted, but the shaft portion 56b is loosely fitted. If possible, it may be slightly different from the convenience of forming the retaining ring 58. As shown in FIG. 3, the retaining ring 58 is formed with a slit 59 at one place in the circumferential direction so that it can be elastically expanded and contracted. FIG. 3 shows the retaining ring 58 in a natural state before being attached to the roller 57. After the plurality of cylindrical rollers 56 are arranged on the flange portion 57a of the roller 57 in the circumferential direction, the retaining ring 58 is slightly reduced in diameter in the radial direction from the natural state so that the outer peripheral edge of the retaining ring 58 becomes the groove portion 57e of the roller 57. By inserting, the retaining ring 58 is attached to the roller 57. The outer peripheral edge of the retaining ring 58 is expanded in diameter by the elastic restoring force of the retaining ring 58 itself, and comes into pressure contact with the bottom of the groove 57e of the roller 57. In a state where the retaining ring 58 is attached to the roller 57, the gap of the slit 59 of the retaining ring 58 is made sufficiently smaller than the diameter of the shaft portion 56b of the cylindrical roller 56. Further, the position of the inner peripheral surface of the retaining ring 58 and the position of the inner peripheral surface of 56 are substantially matched in the radial direction. In a state where the roller 57 is not inclined with respect to the leg shaft 55, the equator portion of the spherical surface portion 55a of the leg shaft 55 is preferably in contact with the outer peripheral surface of the cylindrical roller 56 in the axial direction center. A contact ellipse whose major axis is parallel to the axial direction of the leg shaft 55 is formed at the contact portion.

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, only the shape of the spherical surface portion 55a of the leg shaft 55 is changed, and the rest is the same as the first embodiment of FIG. That is, a belt-like intermediate curved surface portion 55b having a curvature radius R2 larger than the curvature radius R1 of the spherical surface portion 55a is formed with a predetermined width at the central equator portion of the spherical surface portion 55a on the outer periphery of the leg shaft. The intermediate curved surface portion 55b formed on the true spherical surface portion 55a of the leg shaft 55 is a region where the cylindrical roller 56 is always in contact with the maximum surface pressure. That is, when the tripod 54 transmits rotational force to the housing 51 at a normal operating angle (about 2 to 10 deg), the width (shaft) of the cylindrical roller 56 that receives the load mainly contacts the intermediate curved surface portion 55b. Direction dimension) is set. The intermediate curved surface portion 55b is a curved surface having a gentler curvature than the true spherical surface portion 55a, and its curvature radius R2 is preferably about 2 to 5 times the curvature radius R1 of the true spherical surface portion 55a. The maximum outer diameter of the intermediate curved surface portion 55b is It is set smaller than the outer diameter of the true spherical surface portion 55a.
Accordingly, the cylindrical roller 56 contacts the intermediate curved surface portion 55b during operation angle operation of the tripod 54, and the maximum surface pressure at this time is larger than the maximum surface pressure when the cylindrical roller 56 contacts the true spherical surface portion 55a having a small curvature radius. Get smaller. That is, the cylindrical roller 56 makes contact closer to point contact with the true spherical surface portion 55a having a small curvature radius R1, but makes contact closer to surface contact with the intermediate curved surface portion 55b having a larger curvature radius R2. . By doing in this way, the surface pressure between the intermediate | middle curved surface part 55b and the cylindrical roller 56 can be reduced, and a joint lifetime can be increased.

  Next, a third embodiment of the present invention will be described with reference to FIG. In this embodiment, a second retaining ring 60 is attached in place of the flange portion 57 a of the roller 57. This second retaining ring 60 can be used by inverting the same one as the first retaining ring 58 upside down. In order to attach the second retaining ring 60 to the roller 57, a second groove portion 57 f is formed on the inner diameter surface of the roller 57. By attaching the two retaining rings 58 and 60 to the roller 57 in this way, the direction of the roller 57 itself can be eliminated to improve the assembly workability, and the weight of the roller 57 can be reduced.

  The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, in the first embodiment of FIG. 1, the flange portion 57a of the roller 57 is formed on the side close to the joint center. However, the roller 57 can also be used with the roller 57 turned upside down in FIG. Further, as a guide portion for guiding the shaft portions 56a and 56b at both ends of the cylindrical roller 56 so as to be movable in the circumferential direction of the roller 57, a combination of the annular groove portion 57b of the flange portion 57a of the roller 57 and the annular groove portion 58a of the retaining ring 58, Although the combination of the annular groove portions of the two retaining rings 58 and 60 has been exemplified, other guide portions may be configured instead of these. For example, another flange portion is formed on the roller 57 of FIG. 1 on the opposite side in the same manner as the flange portion 57a, an annular groove portion is formed on the pair of flange portions, and the shaft portion 56a of the cylindrical roller 56 is formed on the inner surface of the flange portion. You may form in the circumferential direction part so that the groove part of the radial direction for inserting 56b may be connected to an annular groove part. The groove in the radial direction can be closed with another member after the cylindrical roller 56 is assembled to the roller 57.

The cross-sectional view of the tripod type constant velocity universal joint which shows 1st embodiment. The principal part expanded sectional view of FIG. The top view of a retaining ring. The cross-sectional view of the tripod type constant velocity universal joint which shows 2nd embodiment. The cross-sectional view of the tripod type constant velocity universal joint which shows 3rd embodiment. 1 shows a conventional single roller type sliding constant velocity universal joint, wherein (A) is a cross-sectional view of the joint, and (B) is a vertical cross-sectional view of the joint (A) with the operating angle θ taken. is there. The conventional double roller type sliding constant velocity universal joint is shown, (A) is a cross-sectional view of the joint, and (B) is a cross-sectional view perpendicular to the leg shaft of the roller cassette.

Explanation of symbols

51 Housing 52 Track groove 53 Roller guide surface 54 Tripod 55 Leg shaft 55a Spherical surface portion 55b Intermediate curved surface portion 56 Cylindrical roller 56a Shaft portion 56b Shaft portion 57 Roller 57a Flange portion 57b Annular groove portion 57c R surface 57d R groove 57e Groove portion 57f Groove portion 58 Stop Ring 58a Annular groove 59 Slit 60 Retaining ring 62 Boss

Claims (6)

A hollow cylindrical housing that is fixed at the end of the first rotating shaft and that is formed at one end side in the axial direction and has a concave groove extending in the axial direction at a circumferentially equally divided position on the inner peripheral surface;
A tripod having a boss fixed to the end of the second rotating shaft and a leg shaft protruding in a radial direction from a circumferentially divided position of the boss;
In a tripod type constant velocity universal joint that is fitted to the outer peripheral surface of the leg shaft and is accommodated in a concave groove of the housing and is capable of rolling in the housing axial direction,
A spherical portion formed on the outer peripheral surface of the tripod leg shaft;
A plurality of rollers disposed in an annular space between the spherical surface portion of the leg shaft and the inner surface of the roller;
A shaft portion protruding from the center of both ends of the roller in the axial direction of the roller;
A tripod type constant velocity universal joint provided with a guide portion that guides the shaft portion so as to be movable in the circumferential direction of the roller.   The tripod type constant velocity universal joint according to claim 1, wherein a belt-shaped intermediate curved surface portion having a radius of curvature larger than the radius of curvature of the spherical portion is formed at a predetermined width at the central equator portion of the spherical portion.   The tripod type constant velocity universal joint according to claim 1 or 2, wherein the guide portion is constituted by a pair of annular groove portions that receive shaft portions at both ends of the roller.   4. The tripod constant velocity universal joint according to claim 3, wherein at least one of the pair of annular grooves is formed on an inner surface of a retaining ring fixed to an inner diameter surface of the roller.   4. The tripod constant velocity universal joint according to claim 3, wherein one of the pair of annular grooves is formed on an inner surface of a flange portion integrally formed with an inner diameter surface of the roller.   The tripod type constant velocity universal joint according to claim 4, wherein the retaining ring is elastically expandable and contractible by forming a slit at one place in the circumferential direction.

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